Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have invented a new foam, called Oleo Sponge, that not only easily absorbs oil from water, but is also reusable and can pull dispersed oil from the entire water column — not just the surface.
Researchers already have a library of molecules that can grab oil, but the problem is how to get them into a useful structure and bind them there permanently.
The scientists started out with common polyurethane foam, used in everything from furniture cushions to home insulation. This foam has lots of nooks and crannies, like an English muffin, which could provide ample surface area to grab oil; but they needed to give the foam a new surface chemistry in order to firmly attach the oil-loving molecules.
Previously, the scientists had developed a technique called sequential infiltration synthesis, or SIS, which can be used to infuse hard metal oxide atoms within complicated nanostructures.
After some trial and error, they found a way to adapt the technique to grow an extremely thin layer of metal oxide “primer” near the foam’s interior surfaces. This serves as the perfect glue for attaching the oil-loving molecules, which are deposited in a second step; they hold onto the metal oxide layer with one end and reach out to grab oil molecules with the other.
The result is the Oleo Sponge, a block of foam that easily adsorbs oil from the water. The material, which looks a bit like an outdoor seat cushion, can be wrung out to be reused — and the oil itself recovered.
At tests at a giant seawater tank called Ohmsett, the National Oil Spill Response Research & Renewable Energy Test Facility, located in New Jersey, the Oleo Sponge successfully collected diesel and crude oil from both below and on the water surface.
According to the scientists, the material is sturdy. They have run dozens to hundreds of tests, wringing it out each time, and have yet to see it break down at all.
Oleo Sponge could also potentially be used routinely to clean harbors and ports where diesel and oil tend to accumulate from ship traffic.